1. Field of the Invention
This invention relates to a method for recycling recovered discs, each including two disc substrates bonded together by an adhesive, such as a DVD (Digital Versatile Disc), a flame retardant resin composition, and a flame retardant resin molded product, recycled by such method.
2. Description of Related Art
DVD-Video, DVD-Audio, DVD-ROM, DVD±R, DVD±R/W and DVD-RAM, for example, collectively termed a DVD, are finding widespread use as a medium for reproducing or recording pictures, music or data. As a matter of course, the DVDs, if used up, have to be disposed of in large quantities as a waste material in the same way as conventional tape-shaped mediums, such as VHS tapes, 8 mm tapes or music tapes.
Meanwhile, the DVD is of a structure composed of two disc substrates bonded together with an adhesive. In addition, there are contained in the DVDs a large variety of film materials, such as reflective films, recording films, or printing ink, formed on the disc substrate. Hence, if a DVD is recovered and reused as the starting material for the disc, the above additives are mixed as foreign matter, thus posing a problem that optical properties of high reliability may not be achieved.
Thus, there have so far been proposed a wide variety of techniques for exfoliating and removing the above additives contained in the recovered discs by treatment thereof with suitable chemicals (see, for example, the Patent Publications 1 to 7).
However, these conventional methods use a large quantity of chemicals and yield a large quantity of liquids and, therefore, are a problem from the perspective of saving resources or environmental protection. In addition, these techniques are mostly directed to a disc including a sole disc substrate, such as CD-DA, CD-R, CD-ROM, CD-R/W or CD-RAM, referred to below collectively as CDs, and cannot be directly applied to a DVD obtained by tightly bonding two disc substrates together using an adhesive.
Under the above circumstances, it is strongly desired for the public interest that the DVDs, estimated to be recycled in the future in large quantities, will be recycled efficaciously.
[Patent Publication 1] Japanese Laid-Open Patent Publication H7-205154
[Patent Publication 2] Japanese Laid-Open Patent Publication 2003-200133
[Patent Publication 3] Japanese Laid-Open Patent Publication H5-217219
[Patent Publication 4] Japanese Laid-Open Patent Publication 2001-287225
[Patent Publication 5] Japanese Laid-Open Patent Publication H11-57683
[Patent Publication 6] Japanese Laid-Open Patent Publication H8-164524
[Patent Publication 7] Japanese Patent 3270037